JP5688685B2 - Surface coated cutting tool - Google Patents

Description

  In the present invention, the structure of the hard coating layer is a predetermined laminated structure in which the orientation and composition are specified, so that even when used under severe cutting conditions such as high-speed heavy cutting such as carbon steel where tip wear is likely to proceed, The present invention relates to a surface-coated cutting tool (hereinafter referred to as a coated tool) in which a hard coating layer exhibits excellent thermal crack resistance, welding defect resistance, and wear resistance, and can extend the life of the cutting tool.

  Generally, coated tools are used for throwaway inserts that are detachably attached to the tip of cutting tools for drilling and cutting of various materials such as steel and cast iron. There are drills and miniature drills used, as well as solid type end mills used for chamfering, grooving and shoulder machining of work materials, etc. A slow-away end mill tool that performs cutting is known.

As a specific coated tool, for example, a hard film is formed on the surface of a tool base made of tungsten carbide group (hereinafter referred to as WC group) cemented carbide or titanium carbonitride group (hereinafter referred to as TiCN group) cermet. Is generally known to improve wear resistance and tool life of coated tools.
For example, as shown in Patent Document 1, on a tool base surface, a lower layer made of an (Al, Ti) N layer, an intermediate layer made of an (Al, Cr) N layer, and an upper portion made of an (Al, Ti) N layer. By forming a hard coating layer composed of layers, the lower layer improves high temperature hardness, heat resistance, and high temperature strength, and the intermediate layer has high temperature hardness, high temperature strength, high temperature oxidation resistance, and welding resistance. There is known a coated tool that exhibits excellent wear resistance as a synergistic effect of these effects by improving and improving the wear resistance and fracture resistance of the upper layer.
Moreover, as shown in Patent Document 2, a hard coating layer composed of a lower layer and an upper layer is formed on the surface of the tool base by vapor deposition, and the lower layer is formed by alternately laminating a thin layer A and a thin layer B. Consists of alternating layers of thin layers A and C, where the thin layer A is either a (Cr, Al) N layer or a (Cr, Al, Si) N layer, and the thin layer B is (Ti, A coated tool having improved chipping resistance and wear resistance by forming either the (Al) N layer or the (Ti, Al, Si) N layer, and the thin layer C comprising the (Ti, Si) N layer. It has been known.

JP 2009-125832 A JP 2010-207918 A

  In recent years, the use of FA for cutting devices has been remarkable. On the other hand, there has been a strong demand for labor saving and energy saving and further cost reduction for cutting, and with this, cutting tends to become more efficient. In the case of a coated tool, there is no problem when it is used for cutting under normal conditions, but this is accompanied by the high heat generation of a high-hardness work material such as carbon steel, and the cutting edge is high. When used under high feed and high cutting conditions where the load is applied, the hard coating layer is overheated by the high heat generated during cutting, resulting in a decrease in high-temperature hardness and insufficient lubricity. As a result, in addition to the inevitable deterioration of the welding defect resistance, since the adhesion between the hard coating layer and the tool surface is not sufficient, the service life is reached in a relatively short time.

  In view of the above, the inventors of the present invention used high-hardness work materials such as carbon steel in high-speed heavy cutting conditions that generate high heat and a high load acts on the cutting edge. Even in this case, the following knowledge was obtained as a result of conducting research while focusing on the conventional coated tool in order to develop a coated tool exhibiting excellent thermal crack resistance and weld defect resistance with an excellent hard coating layer.

(B) It is generally known that when the hard coating layer of the coated tool is made of AlTiN, the hard coating layer made of AlTiN is excellent in hardness and toughness and in chemical stability. When a high-hardness work material is used under high-speed heavy cutting conditions that cause high heat generation and a high load acts on the cutting edge, the hardness and toughness cannot be said to be sufficient.
Therefore, the present inventors have a high-temperature hardness and high toughness by forming an AlTiN layer as a lower layer and a layer having a specific composition, orientation and structure as an upper layer, and heat-resistant cracks under high-temperature conditions. It has been found that it has excellent properties and resistance to welding defects.

(B) That is, the average layer thickness is 0.5 to 5 μm, and the composition formula: (Al _1-x Ti _x ) N (where x represents the content ratio of Ti, and the atomic ratio is 0. A lower layer having a composite nitride layer of Al and Ti satisfying 25 ≦ x ≦ 0.55),
(C) has a total average layer thickness of 0.2 to 6.0 μm, and
A layer:
Composite nitriding of Al and Ti satisfying the composition formula: (Al _1-x Ti _x ) N (where x is the Ti content and atomic ratio is 0.25 ≦ x ≦ 0.55) Layer,
B layer:
Using an electron emission scanning electron microscope, each crystal grain existing on the polished surface of the coating film perpendicular to the surface of the tool base is irradiated with an electron beam, and the crystal of the crystal grain is compared with the normal of the tool base surface. The crystal angle formed by the normal line of the (200) plane, which is a plane, is measured, and among the measured crystal angles, the measurement inclination angle within the range of 0 to 60 degrees is divided for each 0.25 degree pitch, When represented by an inclination angle distribution graph obtained by summing up the frequencies existing in the section, the highest peak exists in the inclination angle section in the range of 0 to 35 degrees, and the inclination angle in the range of 0 to 35 degrees. The inclination angle number distribution graph in which the total of the frequencies existing in the division occupies a ratio of 45% or more of the entire frequency in the inclination angle frequency distribution graph is shown, and the composition formula: (Al _1-y Cr _y ) N (where y Indicates the content ratio of Cr, and the atomic ratio is 0.25 ≦ y Composite nitride layer of Al and Cr satisfying a a a) 0.45,
Each of the A layer and the B layer has a single layer average thickness of 0.05 to 1.5 μm, and is a hard coating composed of an upper layer having a laminated structure of one cycle or more in which the A layer + B layer is one lamination cycle. It has been found that a coated tool provided with a layer has high-temperature hardness and high toughness, and is excellent in heat crack resistance and weld defect resistance under high-temperature conditions.
That is, the (Al, Ti) N layer according to the present invention exhibits sufficient cutting performance even with a single layer, but is combined with the (Al, Cr) N layer having a predetermined orientation from the viewpoint of improving the resistance to welding defects. Cover.
It can be seen that the orientation ratio of the crystal growth orientation affects the cutting performance in a hard coating mainly composed of AlCr. It has been found by the inventors' research that the weld defect resistance improves when the (200) orientation ratio exceeds 45%.
Therefore, when earnestly researching the relationship between the (Al, Ti) N layer and the (200) -oriented (Al, Cr) N layer and the characteristics of the film,
A layer: (Al _1-x Ti _x ) N (0.25 ≦ x ≦ 0.55)
B layer: (200) -oriented (Al _1-y Cr _y ) N (0.25 ≦ y ≦ 0.45)
The average average layer thickness of each layer of the A layer and the B layer is 0.05 to 1.5 μm, and the total average layer thickness is 0.2 to 6 having a laminated structure of one cycle or more in which the A layer + B layer is one lamination cycle. The present invention was completed by combining the upper layer of 0.0 μm with the lower layer having the composite nitride layer of Al and Ti.
The orientation of the deposited (Al _1-y Cr _y ) N is determined by using an electron emission scanning electron microscope, and an electron beam is applied to each crystal grain existing on the polished surface of the film cross section perpendicular to the tool substrate surface. Is measured, and the crystal angle formed by the normal of the (200) plane, which is the crystal plane of the crystal grain, is measured with respect to the normal of the tool base surface. It is possible to confirm by classifying the measured inclination angle within the range of 0.25 degree pitch every 0.25 degree pitch and expressing it by an inclination angle number distribution graph formed by counting the frequencies existing in each section.

(D) Further, the inventors of the present invention have a (Al _{1 -x} Ti _x ) N layer, a (200) orientation, a lower layer made of an (Al _1-x Ti _x ) N layer having a predetermined composition and an average layer thickness. And an upper layer having a layered structure with a predetermined overall average film thickness, each of which has a predetermined film thickness, and a selective (Al _1-y Cr _y ) N layer is selectively formed. When the hard coating layer is formed, the hard coating layer has excellent heat cracking resistance under high feed rate, high cutting and high-speed heavy cutting conditions with high heat generation and high load acting on the cutting edge. It has been found that it exhibits weld resistance deficiency.

The present invention has been made based on the above findings,
“(1) In a surface-coated cutting tool in which a hard coating layer is formed on the surface of a tool base composed of a tungsten carbide-based cemented carbide or a titanium carbonitride-based cermet,
The hard coating layer is
(A) having an average layer thickness of 0.5-5 μm, and
Composite nitriding of Al and Ti satisfying the composition formula: (Al _1-x Ti _x ) N (where x is the Ti content and atomic ratio is 0.25 ≦ x ≦ 0.55) A lower layer composed of physical layers,
(B) having a total average layer thickness of 0.2 to 6.0 μm, and
A layer: compositional formula: (Al _1-x Ti _x ) N (wherein x represents the Ti content, and atomic ratio is 0.25 ≦ x ≦ 0.55) and Al and Ti Composite nitride layer,
Layer B: Using an electron emission scanning electron microscope, each crystal grain existing on the polished surface of the coating film perpendicular to the surface of the tool base is irradiated with an electron beam, and the crystal is normal to the surface of the tool base. The crystal angle formed by the normal line of the (200) plane, which is the crystal plane of the grain, is measured, and the measured tilt angle within the range of 0 to 60 degrees among the measured crystal angles is divided every 0.25 degree pitch. In addition, when represented by an inclination angle distribution graph obtained by summing up the frequencies existing in each section, the highest peak exists in the inclination angle section within the range of 0 to 35 degrees and within the range of 0 to 35 degrees. An inclination angle distribution graph in which the total of the frequencies existing in the inclination angle section occupies a ratio of 45% or more of the entire frequencies in the inclination angle distribution graph is shown, and a composition formula: (Al _1-y Cr _y ) N (here And y represents the content ratio of Cr, and the atomic ratio is 0.2. 5 ≦ y ≦ 0.45) and a composite nitride layer of Al and Cr,
Each layer of the A layer and the B layer has an average layer thickness of 0.05 to 1.5 μm, and is composed of an upper layer having a laminated structure of one cycle or more in which the A layer + B layer is one lamination cycle. A surface-coated cutting tool. "
It has the characteristics.

  Next, the hard coating layer of the coated tool of the present invention will be described.

(A) Lower layer composition and average layer thickness The Al component, which is a component of the (Al, Ti) N layer constituting the lower layer, improves the high temperature hardness of the hard coating layer, and the Ti component has a high temperature strength. However, if the x value indicating the proportion of Ti is less than 0.25 in terms of the total amount with Al (atomic ratio, the same shall apply hereinafter), a predetermined high-temperature hardness can be ensured. However, this causes a decrease in wear resistance. On the other hand, if the x value indicating the Ti ratio exceeds 0.55, the Al content ratio is relatively reduced, which is a high temperature required for high-speed heavy cutting. Since the strength could not be ensured and the wear resistance was lowered, the x value was determined to be 0.25 to 0.55.

Further, if the average layer thickness of the lower layer is less than 0.5 μm, it is insufficient to exhibit its excellent wear resistance over a long period of time, while if the average layer thickness exceeds 5.0 μm In the high-speed heavy cutting described above, chipping is likely to occur at the cutting edge, so the average layer thickness was determined to be 0.5 to 5.0 μm.
The lower layer of such a hard coating layer is, for example, a base is placed in an arc ion plating apparatus which is one type of physical vapor deposition apparatus shown in the schematic explanatory diagram in FIG. While being heated to a temperature of 500 ° C., a cathode electrode (evaporation source) made of an Al—Ti alloy having a predetermined composition is placed in the apparatus, and, for example, an electric current is applied between the anode electrode and the cathode electrode (evaporation source): A condition in which arc discharge is generated under the condition of 90 A and nitrogen gas is simultaneously introduced into the apparatus as a reaction gas to form a reaction atmosphere of 2 Pa, for example, while a bias voltage of, for example, −100 V is applied to the substrate It can be formed by vapor deposition.

(B) Composition and average film thickness of upper layer Thereafter, when A layer: (Al, Ti) N layer and B layer: (200) orientation (Al, Cr) N layer, one A layer and B layer are laminated. An upper layer composed of an alternately laminated structure having one or more periods as a period is configured. The upper layer composed of such an alternately laminated structure can be formed by, for example, arc ion plating under the following conditions.

Deposition conditions:
Cathode electrode: Al—Cr alloy, Al—Ti alloy Reaction gas: N ₂ ,
Reaction gas pressure: 0.5 to 15 Pa,
Bias voltage: −10 to −300V
Here, for the (Al, Cr) N layer formed with the cathode electrode made of an Al—Cr alloy and the reaction gas pressure of 0.5 to 1.5 Pa or 7 to 15 Pa, an electron emission scanning electron microscope was used. An electron beam is irradiated to each of the crystal grains present on the polished surface of the film perpendicular to the surface of the substrate, and the normal line of the (200) plane that is the crystal plane of the crystal grain with respect to the normal line of the tool substrate surface Is measured, and the measured tilt angles within the range of 0 to 60 degrees of the measured crystal angles are divided every 0.1 degree pitch, and the frequencies existing in each section are totaled. When the inclination angle number distribution graph is expressed, the highest peak exists in the inclination angle section in the range of 0 to 35 degrees, and the total of the frequencies existing in the inclination angle section in the range of 0 to 35 degrees is the inclination. 45% of the total frequency in the angle distribution graph It was confirmed to show an inclination angle frequency distribution graph in a proportion above.
The Cr component, which is a component of the (Al, Cr) N layer constituting the B layer in the upper layered structure, improves the high temperature hardness of the hard coating layer, and the Al component improves the high temperature strength. However, when the y value indicating the ratio of Cr is less than 0.25 in the ratio of the total amount with Al (atomic ratio, the same applies hereinafter), the predetermined high-temperature hardness cannot be secured, On the other hand, if the y value indicating the Cr ratio exceeds 0.45, the Al content ratio is relatively decreased, and the high temperature strength required for high speed heavy cutting is ensured. Therefore, it is difficult to prevent the occurrence of chipping, so the y value was set to 0.25 to 0.45.
The Al component, which is a component of the (Al, Ti) N layer that constitutes the A layer in the laminated structure of the upper layer, improves the high temperature hardness of the hard coating layer, and the Ti component improves the high temperature strength. However, when the x value indicating the proportion of Ti is less than 0.25 in the proportion of the total amount with Al (atomic ratio, the same shall apply hereinafter), the predetermined high-temperature hardness cannot be secured, On the other hand, if the x value indicating the Ti ratio exceeds 0.55, the Al content ratio is relatively reduced, and the high-temperature strength required for high-speed heavy cutting is ensured. X value was determined to be 0.25 to 0.55.

In addition, if the average layer thickness of each layer constituting the laminated structure of the upper layer is less than 0.05 μm, it is insufficient for exhibiting its excellent wear resistance over a long period of time. When the layer thickness exceeds 1.5 μm, in high-speed heavy cutting, a lack of welding resistance becomes obvious, and chipping tends to occur at the cutting edge, so that the average layer thickness is 0.05-1. It was set to 5 μm.
Further, when the A layer: (Al, Ti) N layer and the B layer: (200) orientation (Al, Cr) N layer are used, the A layer + B layer has a laminated structure of one period or more with one lamination period. When the total average layer thickness of the upper layer of the hard coating layer is less than 0.2 μm, sufficient wear resistance cannot be exhibited over a long period of use, while the total average layer thickness is 6.0 μm. Exceeding that, especially in difficult-to-cut materials such as carbon steel is accompanied by large heat generation, and high-speed heavy cutting with high load tends to cause chipping at the cutting edge portion. It was determined to be 2 to 6.0 μm.

In the coated tool of the present invention, the hard coating layer has (a) an average layer thickness of 0.5 to 5 μm, and a composition formula: (Al _1-x Ti _x ) N (where x is Ti A lower layer made of a composite nitride layer of Al and Ti satisfying the content ratio and satisfying an atomic ratio of 0.25 ≦ x ≦ 0.55, and (b) a total of 0.2 to 6.0 μm It has an average layer thickness, and layer A: composition formula: (Al _1-x Ti _x ) N (where x represents the content ratio of Ti, and the atomic ratio is 0.25 ≦ x ≦ 0.55 A composite nitride layer of Al and Ti that satisfies the following conditions: B layer: An electron emission scanning electron microscope is used to irradiate individual crystal grains existing on the polished surface of the film cross section perpendicular to the surface of the tool substrate with an electron beam. Then, the crystal angle formed by the normal of the (200) plane that is the crystal plane of the crystal grain is measured with respect to the normal of the tool base surface, and the measured crystal angle When the measured inclination angle within the range of 0 to 60 degrees is divided for each 0.25 degree pitch, and the degree of inclination existing in each division is represented by an inclination angle number distribution graph, 0 The highest peak exists in the inclination angle section within the range of ˜35 degrees, and the sum of the frequencies existing in the inclination angle section within the range of 0 to 35 degrees is 45% or more of the entire degrees in the inclination angle frequency distribution graph. The inclination angle number distribution graph which occupies the ratio is shown, and the composition formula: (Al _1-y Cr _y ) N (where y represents the Cr content ratio, and the atomic ratio is 0.25 ≦ y ≦ 0.45. Each of the composite nitride layer of Al and Cr, A layer, and B layer satisfying (1) has an average layer thickness of 0.05 to 1.5 μm, and A layer + B layer is 1 by comprising a top layer having a periodic or more layered _{structure, (Al 1-x} Ti ) N layer contributes to the improvement of the thermal crack resistance during steel cutting, (200) orientation _{(Al 1-y Cr y)} N layer contributes to the improvement of the welding resistance defective during steel cutting, further, these By making this layer into a laminated structure, it is possible to improve the thermal crack resistance, weld defect resistance and wear resistance.

It is a schematic front view of the arc ion plating apparatus used for forming the hard coating layer which comprises a coating tool. (Al, Cr) N layer of the present invention: An inclination angle number distribution graph for the (200) plane in the B layer.

  Next, the coated tool of the present invention will be specifically described with reference to examples.

As raw material powders, WC powder, Co powder, TiC powder, TaC powder, NbC powder, VC powder, Cr ₃ C ₂ powder, and WC powder each having an average particle diameter of 1 to 3 μm are prepared. , Blended in the composition shown in Table 1, wet-mixed for 72 hours in a ball mill, dried, and then pressed into a green compact at a pressure of 100 MPa, and the green compact was vacuumed at 6 Pa, temperature: 1400 ° C. The tool base A1 made of WC-based cemented carbide with ISO standard / SEEN1203AFEN1 chip shape after the sintering is subjected to a honing process of R: 0.03 on the condition of holding for 1 hour. ~ A5, and after sintering, the tool base A6 made of WC-base cemented carbide with ISO standard / CNMG120408-MS chip shape by applying R: 0.8 honing to the cutting edge part ~ A10 was formed.

In addition, as raw material powders, all of Co powder, Ni powder, ZrC powder, TaC powder, NbC powder, Mo ₂ C powder, WC powder and TiCN having an average particle diameter of 0.5 to 2 μm (by mass ratio, TiC / TiN = 50/50) powder is prepared, and these raw material powders are blended in the blending composition shown in Table 2, wet mixed by a ball mill for 24 hours, dried, and then pressed into a compact at a pressure of 100 MPa. The green compact was sintered in a nitrogen atmosphere of 2 kPa at a temperature of 1500 ° C. for 1 hour. After sintering, the cutting edge portion was subjected to a honing process of R: 0.03 and ISO standard / SEEN1203AFEN1. Tool bases B1 to B3 made of TiCN-based cermets having the following chip shape, and after sintering, the cutting edge portion is subjected to a honing process of R: 0.8 and ISO standard / CNMG1204 Tool bases B4 to B6 made of WC-base cemented carbide having a chip shape of 08-MS were formed.

(A) Next, each of the tool bases A-1 to A-10 and B-1 to B-6 is ultrasonically cleaned in acetone and dried, and then the arc ion plating apparatus shown in FIG. It is mounted along the outer periphery at a position that is a predetermined distance in the radial direction from the central axis on the inner rotary table, and cathode electrodes (evaporation sources) are arranged on both sides facing each other across the rotary table. Has an Al-Cr alloy for forming an upper layer having a predetermined composition as a cathode electrode (evaporation source), and Al-Ti for forming upper and lower layers having a predetermined composition as a cathode electrode (evaporation source). An alloy is disposed, and a Ti alloy is disposed as a cathode electrode (evaporation source) for cleaning the Ti bombard on the side facing the heater,
(B) First, the inside of the apparatus is heated to 500 ° C. with a heater while the inside of the apparatus is evacuated and kept at a vacuum of 0.1 Pa or less, and then the tool base that rotates while rotating on the rotary table is −1000 V. A DC bias voltage is applied and a current of 100 A is passed between the Ti alloy of the cathode electrode for Ti bombard cleaning and the anode electrode to generate an arc discharge, thereby cleaning the tool base surface with Ti bombard.
(C) Next, nitrogen gas is introduced as a reaction gas into the apparatus to form a reaction atmosphere of 4 Pa, a DC bias voltage of −100 V is applied to the tool base that rotates while rotating on the rotary table, and An arc discharge is generated by flowing a current of 120 A between the Al—Ti alloy of the cathode electrode and the anode electrode, and a lower portion as a single layer having the target composition and target layer thickness shown in Table 3 is formed on the surface of the tool base. After the (Al, Ti) N layer as a layer is formed by vapor deposition with an average layer thickness of 0.5 to 5 μm, the arc discharge between the cathode electrode (evaporation source) and the anode electrode is stopped,
(D) Next, nitrogen gas is introduced as a reaction gas into the apparatus to form a reaction atmosphere of 0.5 to 1.5 Pa or 7 to 15 Pa, and between the Al—Ti alloy of the cathode electrode and the anode electrode. Arc current is generated by alternately supplying a current of 100 A to the Al—Cr alloy of the cathode electrode and the anode electrode. In this manner, the (Al, Ti) N layer and (Al, Cr) N layer having the target layer thickness shown in Table 3 are alternately deposited on the tool base that rotates while rotating on the rotary table. By
The present invention coated tools 1 to 16 (hereinafter referred to as present invention chips 1 to 16) having a throwaway tip shape defined in ISO · SEEN1203AFEN1 and ISO · CNMG120408-MS were produced, respectively.

For the purpose of comparison, each of the tool bases A1 to A10 and B1 to B6 is cleaned by Ti bombarding in the same manner as the present invention,
Next, nitrogen gas is introduced into the apparatus as a reaction gas to make a reaction atmosphere of 4 Pa, a DC bias voltage of −100 V is applied to the rotating tool base while rotating on the rotary table, and the cathode electrode An arc discharge is generated by passing a current of 120 A between the Al—Ti alloy and the anode electrode, and the surface of the tool base is formed as a lower layer as a single layer having a target composition and a target layer thickness shown in Table 4. After vapor-depositing the (Al, Ti) N layer with an average layer thickness of 0.5 to 5 μm, the arc discharge between the cathode electrode (evaporation source) and the anode electrode is stopped,
Next, nitrogen gas is introduced as a reaction gas into the apparatus, and an arc discharge is performed by alternately supplying a current of 100 A between the Al—Ti alloy and anode electrode of the cathode electrode and between the Al—Cr alloy and anode electrode of the cathode electrode. Is generated. In this way, the (Al, Ti) N layer and the (Al, Cr) N layer having the target layer thickness shown in Table 4 are alternately deposited on the tool base that rotates while rotating on the rotary table. By
Comparative coating tools 1 to 16 (hereinafter referred to as comparative tips 1 to 16) having a throwaway tip shape defined in ISO · SEEN1203AFEN1 and ISO · CNMG120408-MS were produced.

Next, the chips 1 to 5, 11 to 13 of the present invention and the comparative chips 1 to 5, 11 are compared with the above various coated chips screwed to the tip of the tool steel tool with a fixing jig. About ~ 13
Work material: JIS / S50C plate material,
Cutting speed: 300 m / min,
Cutting: radial direction (ae) 100 mm, axial direction (ap) 3 mm,
Feed per tooth (fz): 0.3 mm / tooth,
Dry high-speed high-feed milling test of carbon steel under air blow conditions (cutting condition B) (normal cutting speed and feed are 180 m / min, ae: 80 mm, ap: 1.5, fz: 0.00 2mm / tooth),
The cutting length until the flank wear width of the cutting edge reached 0.2 mm was measured. The measurement results are shown in Table 5.
Moreover, in the state where all of the various coated chips are screwed to the tip of the tool steel tool with a fixing jig, the chips 6 to 10 and 14 to 16 of the present invention and the chips 6 to 10 and 14 of the comparative example are used. About 16
Work material: JIS / S45C round material,
Cutting speed: 250 m / min,
Incision (ap): 1.5 mm,
Feed (f): 0.3 mm / rev
Dry high-speed continuous turning test of carbon steel under air blow conditions (cutting condition B) (normal cutting speed and feed are 150 m / min, ap: 1.5, fz: 0.1 mm / rev, respectively)
The cutting time until the flank wear width of the cutting edge reached 0.2 mm was measured. The measurement results are shown in Table 5.

From the results shown in Tables 3 to 5, the coated tool of the present invention is a high-hardness work material such as carbon steel. Even when machined under heavy cutting conditions, the hard coating layer has excellent thermal crack resistance and welding defect resistance, and exhibits excellent wear resistance over a long period of time. It is clear that when a high-hardness work material is machined under high-speed heavy cutting conditions, the service life will be reached in a relatively short time due to lack of hardness, lubricity and toughness, due to occurrence of welding, chipping, etc. is there.
In addition, not only the coated chip, but also a coated end mill and a coated drill were produced, and the same cutting test was performed. As a result, the same results as the coated chip were obtained for the coated end mill and the coated drill.

  As described above, the coated tool of the present invention not only cuts general steel and ordinary cast iron, but also involves high heat generation of a high-hardness work material such as carbon steel, and a high load acts on the cutting blade. Even when used for high-speed heavy cutting, it exhibits excellent thermal crack resistance and weld defect resistance over a long period of time and exhibits excellent cutting performance. It can be used satisfactorily for labor saving, energy saving, and cost reduction.

Claims (1)

In a surface-coated cutting tool in which a hard coating layer is deposited on the surface of a tool base composed of a tungsten carbide-based cemented carbide or a titanium carbonitride-based cermet,
The hard coating layer is
(A) having an average layer thickness of 0.5-5 μm, and
Composite nitriding of Al and Ti satisfying the composition formula: (Al _1-x Ti _x ) N (where x is the Ti content and atomic ratio is 0.25 ≦ x ≦ 0.55) A lower layer composed of physical layers,
(B) having a total average layer thickness of 0.2 to 6.0 μm, and
A layer: compositional formula: (Al _1-x Ti _x ) N (wherein x represents the Ti content, and atomic ratio is 0.25 ≦ x ≦ 0.55) and Al and Ti Composite nitride layer,
Layer B: Using an electron emission scanning electron microscope, each crystal grain existing on the polished surface of the coating film perpendicular to the surface of the tool base is irradiated with an electron beam, and the crystal is normal to the surface of the tool base. The crystal angle formed by the normal line of the (200) plane, which is the crystal plane of the grain, is measured, and the measured tilt angle within the range of 0 to 60 degrees among the measured crystal angles is divided every 0.25 degree pitch. In addition, when represented by an inclination angle distribution graph obtained by summing up the frequencies existing in each section, the highest peak exists in the inclination angle section within the range of 0 to 35 degrees and within the range of 0 to 35 degrees. An inclination angle distribution graph in which the total of the frequencies existing in the inclination angle section occupies a ratio of 45% or more of the entire frequencies in the inclination angle distribution graph is shown, and a composition formula: (Al _1-y Cr _y ) N (here And y represents the content ratio of Cr, and the atomic ratio is 0.2. 5 ≦ y ≦ 0.45) and a composite nitride layer of Al and Cr,
Each layer of the A layer and the B layer has an average layer thickness of 0.05 to 1.5 μm, and is composed of an upper layer having a laminated structure of one cycle or more in which the A layer + B layer is one lamination cycle. A surface-coated cutting tool.